Conventionally, in a semiconductor device manufacturing process, there has been used a plasma etching method for etching a substrate (e.g., a semiconductor wafer) in a processing chamber by using plasma. By way of example, in the semiconductor device manufacturing process, the plasma etching method has been used to form a contact hole in a silicon dioxide film. When forming a contact hole, there has been a requirement for a HARC (High Aspect Ratio Contact). However, it has been difficult to form a contact hole having a high aspect ratio while preventing a bowing from occurring and maintaining a vertical sidewall shape thereof.
As for such a plasma etching method, there is known a technique for performing a multi-step etching process by performing a process of forming a protection film by using plasma of a gas having a high deposition property and a process of etching the substrate by using plasma of a gas having a low deposition property (see, for example, Patent Document 1).
Patent Document 1: Japanese Patent Laid-open Publication No. 2006-278436
As stated above, in the semiconductor device manufacturing process, although a contact hole having a high aspect ratio is required, it has been difficult to form a contact hole having a high aspect ratio by plasma etching while preventing occurrence of a bowing and maintaining a vertical sidewall shape thereof.